Preheat oven to 350°. Grease and flour three 9-in. round baking pans. In a large bowl, cream butter, shortening and sugar until light and fluffy, 5-7 minutes. Beat in egg yolks and vanilla. Combine flour and baking soda; add to creamed mixture alternately with buttermilk. Beat until just combined. Stir in coconut and pecans., In another bowl, beat egg whites with clean beaters until stiff but not dry. Fold a fourth of the egg whites into batter, then fold in remaining whites. Pour into prepared pans., Bake until a toothpick inserted in center comes out clean, 20-25 minutes. Cool 10 minutes before removing from pans to wire racks to cool completely., For frosting, beat cream cheese and butter until smooth. Beat in confectioners’ sugar and vanilla until fluffy. Stir in pecans. Spread frosting between layers and over top and side of cake. Store cake in the refrigerator.